Health care systems are responsible for providing preventive, therapeutic and rehabilitation services 1. But, payments for this services must be according to ability to pay 2. Thus, the World Health Organization (WHO) developed the concept of Fairness in financial contribution (FFC) as a one of the three main goals of a health systems 3. Before we describe the FFC, we must first define the household’s Capacity to pay (). Household’s Capacity to pay is defined as household’s total expenditure () minus household’s subsistence expenditures () or household’s food expenditure () (if ).

if:

if:

The ratio of a household’s out-of-pocket (OOP) payments for health to their capacity to pay is defined as the household financial contribution (HFC).

Finally, the FFC index formula is as follows:

The range of FFC index is between 0 and 1. 1 represents the most fairness and 0 represents the most unfairness 4.

Fairness in financing contribution will be achieved if all households pay an equal share of their capacity to pay for health. If HFC exceeds a certain threshold, catastrophic health expenditures (CHE) will be occurred. Based on WHO criteria, CHE occurs when out-of-pocket (OOP) payments for healthcare are more than or equal to 40 % of a household’s capacity to pay (HFC>40%) 4. The lack of prepayment mechanisms for risk pooling and low household capacity to pay are the main factors that increase the possibility of the exposure to catastrophic expenditures 5.